Passing more than one parameter to pthread_create [duplicate]

问题

Possible Duplicate:
Multiple arguments to function called by pthread_create()?
How to pass more than one value as an argument to a thread in C?

I have these structures:

struct Request {
    char buf[MAXLENREQ];
    char inf[MAXLENREQ]; /* buffer per richiesta INF */
    int lenreq;
    uint16_t port; /* porta server */
    struct in_addr serveraddr; /* ip server sockaddr_in */
    char path[MAXLENPATH];
    /*struct Range range;*/
};

struct RequestGet {
    char buf[MAXLENREQ];
    int maxconnect;
    struct Range range;
};

struct ResponseGet{
    char buf[MAXLENDATA];
    //int LenRange;
    int expire;
    char dati[MAXLENDATA];
    struct Range range; 
};

How can I pass them to pthread_create? No matter about the meanings of each field of structures.

pthread_create(&id,NULL,thread_func,????HERE????);

回答1:

You can only pass one parameter, so you generally need to make a function that takes one parameter, even if it just wraps some other calls. You can do this by creating a struct and having the function take a pointer to such a struct.

A basic example to illustrate the point is below. Please note that it is not a complete example, and should not be used as-is! Note, for example, that none of the memory allocated with malloc() is freed.

struct RequestWrapper {
    struct Request *request;
    struct RequestGet *request_get;
    struct ResponseGet *response_get;
};

void thread_func(struct RequestWrapper *rw) {
    // function body here
}

int main(int argc, char *argv[]) {
    struct Request *request = malloc(sizeof(*request));
    struct RequestGet *request_get = malloc(sizeof(*request_get));
    struct ResponseGet *response_get = malloc(sizeof(*response_get));
    ...

    struct RequestWrapper *wrapper = malloc(sizeof(*wrapper));

    wrapper->request = request;
    wrapper->request_get = request_get;
    wrapper->response_get = response_get;

    ...

    pthread_create(&id, NULL, thread_func, &wrapper);
    ...
}

回答2:

struct Foo {
   // anything you want
};

void run (void * _arg) {
    Foo * arg = (Foo*) _arg;
    // ...
}

int main () {
    pthread_t thread;
    Foo * foo = create_argument ();

    pthread_create (&thread, NULL, run, foo);
}

This depends, of course, on a contract that run will always be given a Foo* in the last argument to pthread_create.

回答3:

The last argument of pthread_create() is a void pointer. Its designation is that you can let it point to whatever kind of variable, struct etc. Your thread_func knows how to handle it and can cast it back to its original type.

回答4:

Put their addresses into a struct, and pass a pointer to that struct as the last argument to pthread_create().

回答5:

you can just create a structure for all data and pass the address of the structure. you may need to put the structure in the heap and free it when done.

来源：https://stackoverflow.com/questions/8976419/passing-more-than-one-parameter-to-pthread-create

标签

multithreading

parameters

pthreads